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    <script>
        // 使用for循环 - 求出班级里同学们平均年龄[15, 19, 21, 33, 18, 24]
        let age = [15, 19, 21, 33, 18, 24]
        let sum = 0
        let average = 0
        for(let i = 0; i < age.length; i++) {
            sum += age[i]
        }
        average = sum / age.length
        document.write(`班级里同学们平均年龄是${average}`);

    </script>
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